introduction to plc presentation

7/24/2019 Introduction to PLC Presentation

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NikiniNikiniNikiniNikini

INTRODUCTION TOINTRODUCTION TOPROGRAMMABLEPROGRAMMABLE

Nikini Automation Systems (Pvt) LtdIntroduction to PLC 11/19/2010 8:48 AM


Automation Systems (Pvt.) Ltd.


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Overview

Introduction to automation technology Introduction to micro PLC systems

General Structure of PLC System


Installing PLC and configuring hardware CPU memory and data types

Basic programming concepts

Programming languages Programming instructions

Programming of control systems


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Automation Technology



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What is automation?


Automation is aimed at reducing human effort in

performing a task.

Manual Process

Mechanized Process


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What is automation?

Automation (ancient Greek: = self dictated)or industrial automation is the use of

electronic controllers to control industrial


machinery and processes, replacing humanoperators.

It is a step beyond mechanization, wherehuman operators are provided with

machinery to help them in their jobs.


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Where used?

Production Industry Offices

Buildin s


Construction Industry

Medical field

Household equipment

Aerospace Industry

???


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Example of a Manual process

Drillin machine


Manual Process of Drilling a work piece

Work piece

Clamping device


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Processes carried out

Keeping the work piece Clamp the work piece


Un clamp work piece

Remove the work piece

Sensing each operation


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Elements of the manual system

Actuators


Decision making element

Sensors


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Automating the Process:

Step 1 :Replacement of humans muscles (hands) by someactuators, e.g. the pneumatic cylinders

Ste 2 :Re lacement of humans brain b a lo ic si nal


processing device, e.g. PLC, electrical relay circuit.

Step 3 :Replacement of humans senses (eyes, ears, etc.)by some input devices (electrical sensors).

Step 4 :Use set of instructions to control output elementaccording to the signal inputs present.


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Automated SystemDrill Cylinder Limit switches/

sensors to detectend limits of

cylinder movement

Clamp


Operator panel Signal Processor


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Industrial Automation


Pentagon ofAutomation


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Signal Processors

Pro rammable Lo ic

Hard-wired Control Programmable Control


Controller (PLC)Electrical

Pneumatics

Hydraulic

DigitalElectronics Embedded Controller

Micro controller (PIC)

Industrial PC


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Hardwired Control &Programmable Control

Hard-wired control Wiring of mechanical, electrical, electro-

mechanical or electronic com onents to obtain


desired control

Programmable control

Programming and reprogramming of an

electronic component to obtain desired control


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Introduction to PLC



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PLC is an abbreviation for Programmable LogicController.

PLC is a microprocessor-based electronic device.

What is PLC?


This equipment controls a process/ machine. a printing machine for printing newspapers, a bagging

plant to bag cement, a press for pressing plastic-shaped

parts, This process occurs according to the instructions

of a program in the memory of the equipment.


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What is PLC?

PLC is primarily used as an Industrial MachineController.

PLC is a small, but powerful Computer which is


.

To control process/ Machine Sensors

Control switches (Push buttons, Switches)

Actuators (Solenoid Valves, Motor controllers)

should be wired to the PLC

Program with instructions stating how the process/

machine works should be written into the PLC memory

Signal Inputs

SignalOutputs


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Basic Principle of a PLC

Program (Instructions)Program (Instructions)Program (Instructions)Program (Instructions)


Input SignalsInput SignalsInput SignalsInput Signals Signal ProcessingSignal ProcessingSignal ProcessingSignal Processing Output SignalsOutput SignalsOutput SignalsOutput Signals


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Advantages of PLC

Greater Flexibility and reliability

Changes to the design can easily be made on thero ram.


Easy debugging Error detection program available.

Low power consumption & space requirement

Based on solid-state electronics rather than electro-mechanical technology.

Little maintenance

No moving parts.


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Advantages of PLC

No special programming skills required

Computer programming knowledge is not required.


Prices of microprocessor-based devices reduced morethan those of electro-mechanical devices.

Easy Archiving & Documentation Programming, Parameter changes, etc. can be noted and stored in

the computer and documented without effort.


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The SIMATIC S7-200 is the CPU for the lower levelperformance range.

It is available in various grades.

S7-200


machines and system construction. It is real time capable and offers extensive communication

possibilities over a PROFIBUS or PC/PPI cable and over a free

programmable interface protocol.

The SIMATIC S7-200 offers modular extensibility and integratedPID closed loop control functions.

The program software STEP 7 Micro/Win enables a quick

introduction in the programming and configuration.


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The SIMATIC S7-300 family offers the automationsolutions for the lower and middle performance range.

Properties of the SIMATIC S7-300

S7-300


Up to 1024 digital in- and outputs

Multipoint capable interface for the configuration of smaller

networks and for configuration with help of a PC/PG.

Quick execution time in which the performance capable CPU

executes 1024 binary instructions inside of 0.1 ms. Modular configuration and quick enhancements are possible

through interface modules with an integrated back plane bus.


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The CPUs of the family SIMATIC S7-400 build thesolutions for the middle and higher performance range(e.g. automobile and machine tool construction orinstrumentation and control).

S7-400


Properties of the SIMATIC S7-400 Program memory up to 660 K instructions.

Up to 131056 digital in- and outputs.

Multipoint capable interface for the configuration of smallernetworks and for configuration with help of the PC/PG.

Quick execution time that the performance capable CPU executes1024 binary instructions inside of 0.1 s.

Modular configuration and quick enhancements are possiblethrough interface modules with integrated back plane bus.


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Hardware Components of a PLC

A PLC is made up of two basic sections Input/Output (I/O) Interface


CPU consists of two main parts

Processor

Memory


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Cartridge

Portable EEPROM Battery



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Wiring PLC

Follow the instructions/ manual given bythe manufacturer


, .

Find the required type of inputs (Voltage,

current, etc)

Connect all the modules and wire themodules as pre given instructions


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Niki iNiki iNiki iNiki i


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Hardware Configuration

Configuring connected hardware units anddownloading the firmware into CPU.

Enables CPU to identify the connected


hardware modules and their capabilities.This is essential for using the modules.

S7 200 provides facility to read the PLC

rather than manually configuring eachconnected unit.



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Hardware Configuration

1. Connect wired PLC to Computer2. Set PLC & PG (Computer) Interface


3. Set communication with PLC

4. Configure connected components (or

identify PLC type)5. Download the settings to PLC



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PLC Programming




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Programming Concept

1. Specification: Description of the task2. Design: Description of the solution


.

solution

4. Integration/commissioning: Incorporating

into environment and testing the solution


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Prepare flow chart or ladder

program

Assign Input/ Output terminal

addresses


Write program into PLC

Simulate operation and

debug program

Correct program



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Connect external devices

Trial Run Correct program

Is program correct?

Yes

No


Store program

Run

Is program correct?

Yes

No



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Programming Method

Console orProgramming Keypad

PLCPeripheral DeviceConnecting Cable


Link with Console / Programming Keypad

ProgrammingSoftware

Computer

Link with Computer



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Programming Languages

IEC 61131-3 LanguagesLadder diagram (LD)


Instruction list (IL) Structured text (ST)

Sequential function chart (SFC)



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Comparison of ProgrammingMethodsGraphical Programming (LD, FBD, SFC)

Windows-based graphical programming environment on a

computer, to compose the ladder diagram.


qu ppe w t goo mon tor ng too s an programm ng a s.

Good for program development.

Mnemonic Code Programming (IL, ST)

Compact handheld device to key in programming instructions in

mnemonic codes.

Ideal for on-site debugging and minor circuit modification.

Requires knowledge of the programming codes.


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Example

Actuation of a push button (S1) is to cause a lamp (B1) to

be switched on.

The lamp is to be illuminated as long as the push button is


.

B1S1



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YES Function+24V

STARTInput Output


Electrical Circuit

0V

0 (Off) 0 (Off)1 (On) 1 (On)

Truth Table



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Symbolic Addressing For symbolic addressing, the symbol table must be

filled in. Select the symbol table from the operations tree or

by selecting Symbol table in the View menu.



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Example of a Ladder Program

Networks

Contact Coil


Box



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Memory AddressingInputs

I0.0

I0.1

Outputs

Q0.0

Q0.1


.

.

.

.

I0.7

.

.

.

.

Q0.5


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Ladder Programming Rules

Rules about Placing Contacts Each network must begin with a contact.




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Rules about Placing Coils

You cannot begin a network with a coil Coils are used to terminate a network of logic.



coils exist on parallel branches of that particularnetwork. Otherwise there can be only one coil per

network.

You cannot place more than one coil in a series



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Rules about Placing Boxes You cannot begin a network with a box.

Boxes are used to terminate a network of logic.



,

after the box. You can have several boxes with ENO in a series on the

same network.

If a box does not have ENO, rules are similar to that of

a coil. There cannot be more than one box in a network.

You cannot place any instructions after it


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Number of contacts for I / Os , timers, counters, etc. is

unlimited.

Ladder Programming Guide



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An output coil name can only be assigned once. There cannot

be two (or more) coils (or boxes) with same name.





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A network of the ladder diagram is keyed into PLC from

left to right.

Programming for counter and other modules having more

than one input must be performed in a pre-determined order.





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Timer & counter data should be entered at the time of

programming.



Input/output number, step number, timer/counter values,

etc. can be written with only the significant digits.

Timer call with a pre-set

time of 5.5 seconds



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Drawing Lines

You can use the horizontal and vertical lines from

the Program toolbar, or hold down the CTRL key

and press the LEFT, RIGHT, UP, or DOWN


ey on your ey oar , to raw nes

between the elements of your network and the left-hand power rail when necessary to complete a

network.


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Assigning Addresses

To assign a constant value (such as 100) or an absolute

address (such as I0.1), simply type the desired value in theaddress area of the instruction. (Use the mouse or the

ENTER ke to select the address area for t in .




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Compile in LAD

You can compile by using the toolbar

buttons or the PLC menu.




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Example: Burglar Alarm

A thin wire has been stretched behind a display window,

which breaks if a burglary is attempted. A closed circuit is interrupted as a result of this and a


.


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Press with protective guard

A press stamp 1.0 is to advance

only if a push button S1 isactuated and a protective guard


.

If one of these conditions is notmet, the press tool is to returnimmediately.

The position of the closedprotective guard B1 is monitoredby a proximity switch B1.


A i


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AND Function+24V

S1

Input 1 Input 2 Output

0 0 0


0V

S2

Electrical Circuit

1 0 0

1 1 1

Truth Table


AND F i


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AND Function


Ladder Diagram


B ll


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Bell system

An apartment bell is to ring if bell button S1 at the front

door is pressed or bell button S2 at the apartment door.



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OR F ti


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OR Function


Ladder Diagram


F ti Bl k Di


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Function Block Diagram

There are no contacts and coils, but there are

equivalent instructions that appear as boxinstructions.


The program logic is derived from the connections

between these box instructions.

The output from one instruction (such as an AND

box) can be used to enable another instruction

(such as a timer) to create the necessary controllogic.



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YES Function


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YES Function


Functional Block Diagram


NOT Function


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NOT Function




AND Function


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AND Function




OR Function


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OR Function




Statement List


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Statement List

Statement List (STL) editor allows to create

control programs by entering the instructionmnemonics.


This text-based concept is very similar to

assembly language programming.

The CPU executes each instruction, in the order

dictated by the program, from top to bottom, and

then restarts at the top.


Example


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Example


Ladder DiagramStatement List


YES Function


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Statement Logic

YES Function


.

= Q0.0


NOT Function


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Statement Logic

NOT Function


.

= Q0.0


AND Function


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Statement Logic

AND Function


.

A I0.1= Q0.0


AND Function


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Statement Logic

AND Function


.

LD I0.1ALD

= Q0.0


OR Function


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Statement Logic

OR Function


.

O I0.1= Q0.0


OR Function


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Statement Logic

OR Function


.

LD I0.1OLD

= Q0.0


LD Language


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LD Language

Ladder logic is easy for beginning programmers to

use. Graphical representation is often easy to


understand, and is popular around the world.

The LAD editor can be used with both theSIMATIC and IEC 1131-3 instruction sets.

You can always use the STL editor to display a

program created with the LAD editor.


FBD Language


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FBD Language

The graphical logic gate style of representation is

good for following program flow. The FBD editor can be used with both the


SIMATIC and IEC 1131-3 instruction sets.

You can always use the STL editor to display aprogram created with the LAD editor.

The expandable AND/OR boxes make it easier to

draw complex input combinations.


STL Language


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STL Language STL is most appropriate for experienced programmers.

STL sometimes allows you to solve problems that youcannot solve easily with the LAD or FBD editor.


program that was created with the SIMATIC LAD or FBD

editors, the reverse is not always true.

You cannot always use the SIMATIC LAD or FBD editors

to display a program that was written with the STL editor.


PLC Exercises


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PLC Exercises



Exercise 1: NAND


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S1 S2 B10 0 1


0 1 1

1 0 1

1 1 0


Exercise 1: NOR


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S1 S2 B10 0 1


0 1 0

1 0 0

1 1 0


Exercise 1: X-OR


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S1 S2 B10 0 0


0 1 1

1 0 1

1 1 0


Exercise 2-Logic


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Input 1 Input 2 Input 3 Output 1 Output 21 1 0 1 0

g


0 1 1 1 0

1 0 1 0 1

1 1 1 0 1


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NikiniNikiniNikiniNikiniSilo control system for two bulk

materials


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A mixing plant permits a selection between two

bulk materials per selector switch (S2). In switch position 1 (S2 = 0 signal), bulk material


,actuated simultaneously.

If selector switch S2 is in position 2 (S2 = 1signal) and push button S1 is actuated bulkmaterial B is conveyed.

Silo A is opened via cylinder 1A (solenoid 1M1),Silo B via cylinder 2A (solenoid 2M1).


Programming Concept


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g g p

1. Specification: Description of the task

2. Design: Description of the solution


.

solution4. Integration/commissioning: Incorporating

into environment and testing the solution


Design steps


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1. Sketch the system

2. Identify the sequence3. Design the power circuits


4. Identify the input signals & Output Signals

5. Design the control circuit according to thecontrol requirement

6. If there are signal overlaps, necessary actions

should be taken to overcome signal overlapproblems


materials


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S2 S1 Y1 Y20 0 0 0


0 1 1 0

1 0 0 0

1 1 0 1


Heavy Work piece feeding


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Exercise 3


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1. Piston moves forward when

Start button Pressed

2. Return to initial osition when

A1


Reset button pressed

Y1

NikiniNikiniNikiniNikini+24V

START RESET

1 2 3 4 5


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24V I0 I1 I3I2 I4 I5 I6 I7


0V Q0 Q1 Q3Q2 Q4 Q5 Q6 Q7

0V

Y1


PLC Hardware Components


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Hardware Components of a PLC


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A PLC is made up of two basic sections

Input/Output (I/O) Interface


CPU consists of two main parts Processor

Memory


Input Modules


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Input Modules

Interface for input devices.


DC (or higher voltage) to 5V DC.

Isolate Signal given to the CPU.

Input delay to screen input signals.



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Types of Input modules


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Sink-type input module interfaced with drycontact switches and PNP sensor


Types of Input modules


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Source-type input module interfaced withdry contact switches and NPN sensor


Output Modules


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Output Modules

The signals coming from CPU are 0V or 5V.


Relay/ Transistor/ Triac Output.



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Types of output modules


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Transistor Output (Source Type)


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Relay Output




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Triac Type Output


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Basic Memory AreasThe Basic memory areas of a PLC :The Basic memory areas of a PLC :


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Work Memory (RAM)Work Memory (RAM)

contains the executable user program

CPU


Load MemoryLoad Memory

(EEPROM/RAM)(EEPROM/RAM)

Contains the entireUser Program

System Memory (RAM)System Memory (RAM)

Block stack, Interrupt stack

Diagnostic buffer, Local data stack

process image input/output tables,

bit memory, timers, counters


PLC Memory Bit is the abbreviation for binary digit


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Bit is the abbreviation for binary digit.

The BIT is the smallest binary (bivalent) informationunit.


.

BYTE. A byte has the size of 8 bits.

0 1 0 0 11 1 0


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MSB LSB2021222324252627

PLC Memory


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ByteByte MB100

MS Byte

BitBit 20 0 1 0 0 11 1 0

0


MW100WordWord

Double WordDouble Word MD100MS Byte

LS Byte

LS Byte


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Memory addressing Byte/ Word/ Double word addressing


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Byte/ Word/ Double word addressing

MB0


MB1

VW10VD100

Timer and Counter addressing are different


How the Control Program WorksPLC performs the following operations repeatedly:


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Read the states of the input devices.

-


(PII) register.

CPU execute the user program stored in the LoadMemory and stores the results of the programlogic in various memory areas including Process-

Image Output (PIQ) register. Transfer status from the PIQ to the field outputs.


O S C l

Scan Cycle of the PLC


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One Scan Cycle

Reading the inputs


Executing the program

Process any communication requests

Executes the CPU self test diagnostics

Writing to the outputs


Scan Cycle of the PLC Reading the inputs: The S7-200 copies the state of the physical

i h i i i


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inputs to the process-image input register.

Executing the control logic in the program: The S7-200 executesthe instructions of the program and stores the values in the


.

Processing any communication requests: The S7-200 performs

any tasks required for point-to-point or networkcommunications.

Executing the CPU self-test diagnostics: The S7-200 ensuresthat the firmware, the program memory, and any expansion

modules are working properly. Writing to the outputs: The values stored in the process-image

output register are written to the physical outputs.


The execution of the scan cycle is dependent upon whether the S7-200


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is in STOP mode or in RUN mode. In RUN mode, your program is

executed; in STOP mode, your program is not executed.



The time that the processor requires for this

PLC scan cycle time


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The time that the processor requires for this

execution is called a cycle time.


instructions and types of commands.

Also cycle time is dependent on CPU speed

and I/O conversion time delay


Exercise 41 Piston moves forward when1B2


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1. Piston moves forward when

Start button Pressed

2. Return to initial osition

1B2


automatically when piston

moved to 1B2

1M1


START A2

1 2 3 4 5


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24V I0 I1 I3I2 I4 I5 I6 I7


0V Q0 Q1 Q3Q2 Q4 Q5 Q6 Q7

0V

Y1


1. Piston moves forward when it1B1 1B2

Exercise 5


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. sto oves o wa d w e t

reaches to 1B1

2. Return to initial osition

1B1 1B2


automatically when piston

moved to 1B23. Continuous cycle starts with

S1 (Start) push button

4. Continuous cycle stops withS2 (Stop) push button

1M1


START A1 A2RESET

1 3 4 5 6 7


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24V I0 I1 I3I2 I4 I5 I6 I7


0V Q0 Q1 Q3Q2 Q4 Q5 Q6 Q7

0V

Y1


Counters


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Up Counter (CTU)

Counters


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Down Counter (CTD)


-


Up Counter Counts up from the current value each time thecount-up input CU makes the transition from off toon


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on.

When the current value (Cxxx) is greater than or


,(Cxxx) turns on.

The counter is reset when the Reset (R) input turnson, or when the Reset instruction is executed.

The counter stops counting when it reaches the

maximum value (32,767). Counter ranges:Cxxx=C0 through C255


Example-LAD


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Example-FBD


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Example-STL


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Down Counter Counts down from the current value of thatcounter each time the count down input CD makes


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the transition from off to on. When the current value Cxxx is equal to zero, the


counter bit (Cxxx) turns on.

The counter resets the counter bit (Cxxx) andloads the current value with the preset value (PV)

when the load input (LD) turns on.


Example-LAD


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Example-FBD


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Example-STL


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Up Down Counter Counts up each time the count-up input CU makes the transition fromoff to on.

Counts down each time the count-down input CD makes the transition


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from off to on. The current value Cxx of the counter maintains the current count.


The preset value PV is compared to the current value each time the

counter instruction is executed.

When the current value Cxx is greater than or equal to the preset valuePV, the counter bit Cxx turns on.

Otherwise, the counter bit turns off.

The counter is reset when the Reset (R) input turns on, or when the

Reset instruction is executed. The CTUD counter stops counting whenit reaches PV.


Example-LAD


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Example-FBD


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Example-STL


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Timers


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Timer Types Delay On timer (TON)


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Delay OFF timer (TOF)



Timer NumbersTimer Type Resolution Maximum Time Timer Number

TONR


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1 ms 32.767 s T0, T64


. - , -

100 ms 3276.7 s T5-T31, T69-T95

TON, TOF 1 ms 32.767 s T32, T96

10 ms 327.67 s T33-T36, T97-T100

100 ms 3276.7 s T37-T63, T101-T255


Counts time when the enabling input is ON.

Wh h l (T ) i h

On Delay Timer


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When the current value (Txxx) is greater than orequal to the preset time (PT), the timer bit is ON.


Current value is cleared when the enabling input is

OFF. This timer continues counting after the Preset is

reached, and it stops counting at the maximum

value of 32767.

NikiniNikiniNikiniNikiniExample-LAD


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Example-FBD


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Example- STL


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Delay Off Timer

Delay turning an output OFF for a fixed period of

time after the input turns OFF.

When the enabling input turns ON the timer bit


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When the enabling input turns ON, the timer bitturns ON immediatel and the current value is set


to 0.

When the input turns OFF, the timer counts untilthe elapsed time reaches the preset time.

When the preset is reached, the timer bit turns

OFF and the current value stops counting.



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Example-FBD


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Example-STL


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Counts time when the enabling input is ON.

When the current value (Txxx) is greater than orl t th t ti (PT) th ti bit i ON

Retentive On Delay Timer


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When the current value (Txxx) is greater than orequal to the preset time (PT), the timer bit is ON.


The current value of the Retentive On-Delay timer

is maintained when the input is OFF. A Reset instruction (R) is used to clear the current

value of the Retentive On-Delay timer.



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Example-FBD


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Example-STL


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Exercise 6

1. Delay 3s at 1B1 and move

forward

1B1 1B2


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.

backward

3. Continuous Cycle with S1(Start) push button

4. Stop when 10 cycles

completed5. Stop with S2 (Reset) push

button immediately

1M1


24V I0 I1 I3I2 I4 I5 I6 I7

+24V

START A1 A2RESET

1 3 4 5 6 7


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0V Q0 Q1 Q3Q2 Q4 Q5 Q6 Q7

0V

Y1


materials


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1A

2A


materials Selector switch S2 is used to select between

material A and B.

When a push button S1 is pressed, material A


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should be entered for 13 seconds to the mixing

bin.

Note: What happens if push button S1 is kept

pressed (over 10 or 13 seconds)?


Areas of System Memory

Input Image Register (I)

Output Image Register (Q)

Bit (M) memory


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Special Memory (SM) bits

Timer (T) memory

Counter (C) memory

Analog Inputs (AI) and Outputs (AQ)

Accumulators (AC)

High Speed Counters (HC)Constant Values: Decimal, Hexadecimal, ASCII


Instruction types Bit logic Timer Counter Program Control

Logic Operations Logic Stack


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Logic Stack


Table Conversion High Speed Counter

Interrupt Real Time Clock Math, Increment and Decrement PID Move, Shift, Rotate and Fill

Communication and Networking


Organizing the User Program

Typical User Program StructureMain Program

MENDMain Program : Executed once per scan


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MEND


SBR 0RET

SBR 1RET

INT 0RET

INT 1RET

Subroutine : Executed when called

from the main program

Interrupt Routine : Executed on each

occurrence of the interrupt event


Program Flow

Main Program

CALL 0

SBR 0

RET


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CALL 1

Interrupt Event

MEND

SBR 1

RET

INT 0

RET

NikiniNikiniNikiniNikiniSIMATIC S7-200:

Freeport communication

Option:RS 485 orRS 232 protocol can be us

ed


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Non-Siemens

PLC

Non-Siemensdevice with

RS 485

RS 485

modem

Drive

(e.g. USS protocol)

PLC

ModemPrinter OP

Bar code scanner

RS 485 PPI cable RS 232

NikiniNikiniNikiniNikiniSIMATIC S7-200:

Fieldbus Communication PROFIBUS-DP Slave

AS-I Master


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IT (TCP-IP)

GSM

GPRS


Selecting a PLC

Understand the process to be controlled

1. list the number and types of inputs andout uts.


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2. determine how the process is to be controlled.

3. determine special needs such as distancebetween parts of the process.


Selecting a PLC

Consideration Information to record Notes

1. Proposed system

2. Environmental issues

3. Discrete devices


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. na og evices

5.Specialty modules or features

(application-specific)

6. CPU required

7. I/O locations

8.Communications requirements

9.Programming requirements


Selecting a PLC

Number & types of Inputs and Outputs

Analog Input and Output facility (# and types- V? I?)

Expansion facility (Maximum modules, Module types,..) Function modules available Wei hin Positionin etc.


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Special Functions (HSC, PTO, Real time clock, etc.)

Software

Languages available

Monitoring/ Diagnostic facilities

Other facilities (Wizards, HW Configuration)

Ease of Programming Memory capacity

Speed


Selecting a PLC

Mathematical Calculations

Types of Operator Interface (Operator panels, etc.)

Communication facilities with other PLCs and Computers

T / H idi / Vib i i


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Temperature/ Humidity/ Vibration resistance

Ease of Maintenance

Spare parts/ After sales service/ Reliability/ Shipping time

Cost $$


Selecting a PLC Vendor

If not already specified, a single vendor shouldbe selected. Factors that might be considered

are,


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.

2. support while developing programs

3. the range of products available4. support while troubleshooting

5. shipping times for emergency replacements

6. training

7. the track record for the company

8. business practices (billing, upgrades/obsoleteproducts,etc.)


Review

Introduction to automation technology

Introduction to micro PLC systems

General Structure of PLC System

lli C d fi i h d


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Installing PLC and configuring hardware

CPU memory and data types

Basic programming concepts

Programming languages

Programming instructions

Programming of control systems


Questions??


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Basics

Number systems

Signal Inputs


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PLC memory

PLC scan cycle


Number systems

Decimal

5238 = 5x1000 + 2x100 + 3x 10 + 8x1= 3 2 1 0


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Binary

101101112= 1x27 + 0x26 + 1x25 + 1x24 + 0x23

+ 1x22 + 1x21 + 1x20

= 18310


BCD (Binary Coded Decimal)Decimal number BCD number

010 0000BCD

Number systems

10 BCD


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10 BCD

210 0010BCD

310 0011BCD410 0100BCD

510 0101BCD

610 0110BCD

710 0111BCD

810 1000BCD

910 1001BCD


Decimal number 3564 in BCD

0011 0101 0110 0100 BCD

Number systems

16 bi i d


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16 bits required

BCD coded numbers are often used forseven segment displays and coding

switches.


Hexadecimal

A =10, B =11, C =12, D =13, E =14, F =15

Number systems


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87BC16 = 8x163 + 7x162 + 11x161 + 12x160

=3474810


Types of signals


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Binary signal

Binary signals can take the value of 2 possible states.

Signal state 1 = voltage available = e.g. Switch on

Signal state 0 = voltage not available = e.g. Switch off

In control engineering DC voltage of 24V is used.

+ 24 V = 1 for this input. 0 V = 0


Types of signals

Analog signal


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a og s g a

Can take many values within a certain range

- Examples Temperature -50 ... +150C

Current flow 0 ... 200 l/min

Number of revolutions 500 ... 1500 r/min

These measurements are converted to currents or resistances. analog information are converted to a voltage, current or resistance

value. (analog to digital conversion -A/D conversion.)


Input / Output System

Provides the physical connections between the

outside world and CPU

Input Devices

Output Devices

Selector switches Alarms


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Push buttons

Sensors

Circuit breakers

Level sensors

Relay contactors

Motor starter Contacts

Control Relays

Solenoids

Lights

Horns

Valves

Motor Starters


PLC Operation


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introduction to plc presentation

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